Some problems in the tribology of rough surfaces

Abstract

Parameters such as slopes and curvatures are not intrinsic properties of a surface profile but depend on sampling techniques. Because of the non-stationarity of real surfaces, more fundamental parameters such as roughness and correlation length are also nonintrinsic. This leads to the concept of “functional filtering”, where the roughness used is that of a bandwidth of profile wavelengths defined by the practical problem in hand. Applications to tribological problems such as the contact of journal and roller bearings and the stiffness of machine tool joints are described and discussed. A typology of run-in surfaces based on a random-process characterization is proposed. Finally the application of discriminant analysis to problems not amenable to direct theoretical treatment is discussed and illustrated by an investigation of the failure of lip seals